In a molding process of a resin product, which has an undercut portion, a resin product needs to be removed from molding dies subsequent to opening the molding dies, without damaging the undercut portion. For example, JP-A6-114893 proposes molding dies including multiple dies around an undercut portion. The molding dies are configured to be opened when an undercut portion is removed from the molding dies.
FIG. 13 is a front view showing a molded product 2, which includes a tubular member 1, and one example of a moving path of an inner die 3 according to a prior art. According the prior art, an molding apparatus has an inner die 3 for forming the inner space of the tubular member 1 of the molded product 2. In a case where a molded product 2 does not have a large portion 5, and a tubular member 1 is trapezoid in cross section when taken along an axis of the molded product 2, an inner die 3 can be slid to the left side in FIG. 13 and drawn from an inner space of the tubular member 1 through an end 4, which has a large opening. However, in the structure shown in FIG. 13, a large portion 5 is integrated with the end 4 of the tubular member 1. That is, the molded product 2 has an undercut portion. Accordingly, the inner die 3 cannot be axially drawn from the inner space of the tubular member 1 from the end 4 to the right side in FIG. 13, as imaginarily shown in FIG. 13.